E15
Weishaupt External Control / Communication Fault (e.g., room controller, bus error)

Display shows E15; unit may not respond to thermostat or DHW demand.

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Safety Warning

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

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Possible Causes

Broken communication cable to room controller, Incorrect controller wiring, Incompatible control protocol, Faulty external controller

How to Fix / Troubleshooting

Safety: Turn off power before working on control wiring.

  • Check controller wiring: Locate the low-voltage terminals on the Weishaupt water heater for the room controller or external demand. Verify that the polarity and terminal assignments match the wiring diagram.
  • Inspect cable: Follow the cable to the controller, checking for damage, pinching, or loose connections.
  • Bypass test: If allowed by the manual, temporarily bypass the external controller by fitting a link across the demand terminals to see if the heater operates normally. Remove the link after testing.
  • Controller reset: Reset the external controller according to its manual.
  • Compatibility: Ensure the controller is approved for use with the specific Weishaupt model.
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Repair Difficulty

Medium 3/5

Required Part

Room Controller / Communication Module
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